I got this book as my partner and I both have a ford focus I. Since i've gotten this book I have done the following: tightened my hand brake cable, fixed the cd player, changed a few bulbs and the biggest job i've doen is changed the rear drum brake shoes (albiet with help from my brother).
This book is very handy, but not a one stop shop: I find if you use it in conjunction with the internet is best. The Internet is full of info: some good , some not so good. With this book you can easily screen the good from the bad. Also even if you never attempt the bigger jobs, this book is full of useful tips on the little things that people might take for granted (like how to deal with a streaky windscreen).
Previous to buying this book the biggest job i had done is a mini service of my car (oil change, oil filter and air filter), so I'm not very experienced.